One liter of air containing 4% water vapor by volume(saturated),
contains how much liquid water?
You could calculate this from the ideal gas equation of state, pV = nRT,
p = atmospheric pressure,
V = volume of the sample (= 1 L in this case),
n = the number of moles of gas (unknown in this case),
R = the "universal gas constant," 0.0820575 L atm / (K mol),and
T = the temperature in K; room temperature is about 298 K.
Solving this equation for n tells you how many moles of gas are present. 4%
of that is water. Knowing that water weighs 18 g/mole, you can then
determine the weight of the water in the 1-L sample of air.
How can this be empirically demonstrated?
Two ways I can think of:
1. Put the sealed sample in a freezer, and weigh the frost that forms on
the inside of the container.
2. Place a dessicant in the sealed sample container, and weigh the
dessicant after it has absorbed all the water.
I have been unable to find this concept discussed in any chemistry
references looked up so far. Perhaps you could direct me to a
source where this is talked about.
Here's a really good intro:
You might be able to get something out of these sites as well:
There are many more! Just search on "partial pressure."
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
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Update: June 2012